CN102468831A - Using multi-level pulse width modulated signal for real time noise cancellation - Google Patents
Using multi-level pulse width modulated signal for real time noise cancellation Download PDFInfo
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
- G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
- G10K11/1785—Methods, e.g. algorithms; Devices
- G10K11/17855—Methods, e.g. algorithms; Devices for improving speed or power requirements
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
- G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
- G10K11/1781—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions
- G10K11/17821—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions characterised by the analysis of the input signals only
- G10K11/17823—Reference signals, e.g. ambient acoustic environment
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
- G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
- G10K11/1785—Methods, e.g. algorithms; Devices
- G10K11/17853—Methods, e.g. algorithms; Devices of the filter
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
- G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
- G10K11/1787—General system configurations
- G10K11/17873—General system configurations using a reference signal without an error signal, e.g. pure feedforward
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
- G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
- G10K11/1787—General system configurations
- G10K11/17885—General system configurations additionally using a desired external signal, e.g. pass-through audio such as music or speech
Abstract
A mixed signal processing circuit includes an analog to PWM converting circuit and a finite impulse response (FIR) filter having a multiple output tapped delay line and a summing and integration circuit. The mixed signal processing circuit converts an input analog signal to a PWM signal, forms a multi-level PWM signal from the PWM signal and one or more delayed versions of the PWM signal, and converts the multi-level PWM signal to an output analog signal. The analog to PWM converting circuit is implemented using a triangle waveform generator and a comparator. The FIR filter is implement using a resistive network to apply scaling coefficients of the FIR filter. The mixed signal processing circuit can be implemented within a noise cancellation headphone to generate a noise cancelling signal or generally in applications that would be benefitted from the combination of analog input/output and digital filter techniques.
Description
Technical field
The present invention relates to the mixed signal process field.More specifically, the present invention relates to many level pulse width are used for the field that real-time noise is eliminated.
Background technology
Signal processing relates to the signal executable operations or analyzes.Signal is to change in time or represent with the simulation or the digital electrical of the physical quantity of spatial variations.Digital Signal Processing and analog are the sub-field of signal processing.Digital Signal Processing is used for digitized signal.Analog is used for not digitized as yet signal.More specifically, Digital Signal Processing is represented these signals through the sequence of numeral or symbol with to Signal Processing.Analog is any signal processing of analog signal being carried out through simulation means." simulation " shows the things of the collection that is expressed as successive value on the mathematics.This is different from " numeral " of using a string discrete magnitude to come expression signal.Mixed signal is handled and to be comprised the two element of analog and Digital Signal Processing.The example that mixed signal is handled includes but not limited to comparator, timer, phase-locked loop, analog to digital converter and digital to analog converter.
Not being both between continuous time signal and discrete-time signal basically between the dissimilar signals.In mathematical abstractionsization, the territory of continuous time signal is set of real numbers or its some intervals, and the discrete-time signal territory is set of integers or its some intervals.Often produce discrete-time signal via sampling to continuous time signal.Continuous time signal is the signal of the variation in continued time domain.Discrete-time signal has isarithmic time domain, such as natural number.
Signal processing system can be in amplitude or perhaps continuous for what disperse on the time.Quantizer is used for converting signal to discrete amplitudes from continuous amplitude, and sampler is used for converting signal to discrete time from continuous time.Conventional digital information processing system is discrete in time and discrete on amplitude, but such system is perplexed by aliasing and quantizing noise.The conventional simulation system of processing signals is not perplexed by aliasing and quantizing noise continuously on time and amplitude, but replaces the very high sensitivity that has component tolerance and coupling, lower dynamic range and the difficult reconfigurable property of finite sum.Discrete in time, but continuous conventional system (such as switched-capacitor circuit) is perplexed by aliasing also on amplitude.Discrete on the amplitude, but continuous system still remains a large amount of the exploration on time domain.
Signal processing has many application.A kind of such application is the noise removing head phone that can be used in noisy environment, improving the quality of listening to audio equipment.The high-end noise removing head phone of many routines uses analog component.When eliminating analog signal, apply the noise removing analog signal, wherein this noise removing analog signal inverted signal that is analog signal.Residual error (remaining signal) for after applying inverted signal.Residual quantity is the function of the phase delay between original analog signal to be eliminated and noise removing analog signal.In order to realize the effective noise elimination, it is essential eliminating in real time.If in relatively little phase delay (such as 10 degree), do not apply the noise removing analog signal, then can miss much noise and eliminate.If phase delay is less than this threshold value, then realized good elimination of level.The frequency of signal to be eliminated is high more, then just is difficult to erasure signal more.
The analog component of hundreds of relative high price (about $300) is used in supply at present.Digital form is feasible, but via the result is not good enough or with high costs owing to the requirement of the low delay that real-time noise is eliminated.The digital filter that in noise canceller circuit, uses can provide than the more design flexibility of analog filter, but digital filter is introduced delay and consumed more power.Particularly, the analog-to-digital conversion and the digital-to-analogue conversion that in Analog signals'digital is handled, need need the time, and therefore introduce time delay.In depending on real-time application (such as noise removing), such delay is forbidden.
Summary of the invention
A kind of embodiment of mixed signal treatment circuit comprises and simulates PWM change-over circuit and finite impulse response (FIR) filter.The FIR filter comprises a plurality of output tapped delay line and summation and integrating circuit.The mixed signal treatment circuit is arranged to the input analog signal conversion is become pwm signal, postpones version by one or more of pwm signal and pwm signal and form many level PWMs signal and many level PWMs conversion of signals is become to export analog signal.In certain embodiments, use triangular waveform maker and comparator to realize simulating the PWM change-over circuit.In certain embodiments, use PWM delay line and resistor network to realize that the FIR filter is to use the zoom factor of FIR filter.The mixed signal treatment circuit can be implemented in the noise removing head phone with the generted noise erasure signal.Generally speaking, the mixed signal treatment circuit can be used in the application that from the combination of analog input/output and digital filter techniques, is benefited.
In one aspect, a kind of signal processing circuit is disclosed.This signal processing circuit comprises: change-over circuit is configured to receive input analog signal and the output pulse-width signal corresponding with this analog signal; Delay line is coupled to change-over circuit to receive pulse-width signal, and wherein delay line comprises one or more delay line tap, and each delay line tap is configured to the delay version of output pulse width modulation signal; The convergent-divergent circuit; Be coupled to change-over circuit and one or more delay line tap; Wherein this convergent-divergent circuit be configured to convergent-divergent pulse-width signal and pulse-width signal one or more postpone in version each postpone version, form the pulse-width signal of a plurality of convergent-divergents thus; And summation and integrating circuit; Be coupled to the convergent-divergent circuit, wherein this summation and integrating circuit be configured to receive a plurality of convergent-divergents pulse-width signal, the pulse-width signal of a plurality of convergent-divergents is summed to many level pulse width and converts many level pulse width to the output analog signal.
In certain embodiments, change-over circuit comprises comparator and triangular waveform maker, and wherein comparator is configured to input analog signal and the triangular waveform that receives from the triangular waveform maker are compared, and in response to this comparison the output pulse width modulation signal.In certain embodiments, the cycle of pulse-width signal is corresponding to the cycle of triangular waveform, and the duty ratio in the concrete cycle of pulse-width signal is corresponding to the amplitude of input analog signal during the same period of triangular waveform.In certain embodiments; Postpone version from first of the pulse-width signal of first delay line tap output and postponed the cycle of pulse-width signal with respect to pulse-width signal, and from each in succession each of pulse-width signal of delay line tap output postpone the cycle that version is postponed pulse-width signal in succession in succession.In certain embodiments, the convergent-divergent circuit comprises resistor network.In certain embodiments, summation comprises operational amplifier with integrating circuit.In certain embodiments, summation comprises one or more summing circuit with integrating circuit.In certain embodiments, delay line, convergent-divergent circuit and summation and integrating circuit form finite impulse response filter.In certain embodiments, finite impulse response filter is programmable.In certain embodiments, signal processing circuit is the mixed signal treatment circuit.In certain embodiments, the mixed signal treatment circuit is many level pulse width treatment circuit.
In another aspect, a kind of noise removing head phone is disclosed.This noise removing head phone comprises: microphone is configured to the testing environment noise and generates the input analog signal corresponding with this ambient noise; Signal processing circuit is coupled to microphone; And loud speaker, be coupled to signal processing circuit, wherein this loud speaker is configured to generate audio frequency in response to the output analog signal.This signal processing circuit comprises: change-over circuit is configured to receive input analog signal and the output pulse-width signal corresponding with this analog signal; Delay line is coupled to change-over circuit to receive pulse-width signal, and wherein delay line comprises one or more delay line tap, and each delay line tap is configured to the delay version of output pulse width modulation signal; The convergent-divergent circuit; Be coupled to change-over circuit and one or more delay line tap; Wherein the convergent-divergent circuit be configured to convergent-divergent pulse-width signal and pulse-width signal one or more postpone in version each postpone version, form the pulse-width signal of a plurality of convergent-divergents thus; And summation and integrating circuit; Be coupled to the convergent-divergent circuit; Wherein this summation and integrating circuit be configured to receive a plurality of convergent-divergents pulse-width signal, the pulse-width signal of a plurality of convergent-divergents is summed to many level pulse width and converts many level pulse width to the output analog signal, wherein export the part that analog signal is eliminated the input analog signal basically.
In another aspect, a kind of signal processing method is disclosed.This method comprises: receive the input analog signal; This analog signal conversion is become pulse-width signal; Generate one or more time delay version of pulse-width signal; One or more of convergent-divergent pulse-width signal and pulse-width signal postpones each the delay version in the version, forms the pulse-width signal of a plurality of convergent-divergents thus; The pulse-width signal of a plurality of convergent-divergents is sued for peace to form many level pulse width; And convert many level pulse width to the output analog signal.
Description of drawings
Fig. 1 illustrates the simplified block diagram of the example application of mixed signal treatment circuit in the noise removing head phone.
Fig. 2 illustrates the sketch map according to the mixed signal treatment circuit of an embodiment.
Fig. 3 illustrates two sequential charts that postpone versions of the exemplary pwm signal exported on first three output line in Fig. 2 and pwm signal.
Fig. 4 illustrates the mixed signal treatment circuit of Fig. 2, and wherein summing circuit is coupled between resistor network and the operational amplifier.
Fig. 5 illustrates sequential chart and the exemplary many level PWMs signal of Fig. 3.
The embodiment of mixed signal treatment circuit has been described with respect to some figure of accompanying drawing.When suitable, same reference numerals will be used for representing identical or similar components.
Embodiment
The application's embodiment relates to a kind of mixed signal treatment circuit.One of skill in the art will recognize that the hereinafter of mixed signal treatment circuit specifically described and be merely exemplary and will limit never in any form.Other embodiment of mixed signal treatment circuit will let them originally expect as the those skilled in the art that benefit from present disclosure easily.
Now will concrete implementation with reference to the mixed signal treatment circuit shown in accompanying drawing.Same reference numerals will be used to refer to identical or similar part of generation in the whole text in accompanying drawing and hereinafter specifically describe.For the sake of clarity, and not shown and all conventional characteristics of describing implementation described herein.Certainly will understand; When any such actual execution mode of exploitation, must make the distinctive decision-making of many execution modes so that realize developer's objectives (such as meeting and using the constraint relevant), and these objectives will change along with execution mode with along with the developer with business.In addition, maybe be complicated and consuming time with understanding such development, but will customary engineering design work for the those of ordinary skill of benefiting from present disclosure.
The mixed signal treatment circuit uses following mixed signal mode with relevant with it principle, and this mode has the flexibility that postpones minimum digital filter.Mixed signal treatment circuit and relevant principle can improve wherein the performance of mixed signal chip that must analog filter and reduce the size of these mixed signal chips.Generally speaking, can use the mixed signal treatment circuit to realize the plurality of advantages of Digital Signal Processing.The mixed signal treatment circuit is realized as accuracy of simulation and function low how much attitude processes of optimizing to intensive digital circuit with relevant principle.
In certain embodiments, the mixed signal treatment circuit is used for implementing high-performance and noise removing earphone/head phone chip cheaply.Use hybrid signal processing, a kind of single-chip noise removing solution of not having external component can be provided with quite reasonable price.This mode can be used the noise removing head phone product of affording and is further improved high-end noise removing head phone performance of products.
Though describing aspect the noise removing application, the principle of mixed signal treatment circuit can be applied to other following fields, in these fields, analog input/output will be favourable with the combination of digital filter techniques.Such application includes but not limited to use the mixed signal treatment circuit to improve DC to the performance of DC transducer and reduce the die size of these transducers, in phase-locked loop (PLL) controller, use mixed signal treatment circuit principle and in servo-control system in real time, use mixed signal treatment circuit principle in order to avoid use flash analog/digital converter, flash A/D and microprocessor fast.
Generally speaking, use filter as the signals-modulating device.Filter is through accepting input signal, prevention specified frequency component and transmitting the original signal that is deducted those components that are obstructed to output and come work.Filter is limited their response to the individual frequencies component that constitutes input signal usually.This is called the frequency response of filter.Analog filter is directly to the analog input executable operations and made up by analog component (such as resistor, capacitor and inductor) fully.The example of analog filter is the second order bessel low pass filter.Digital filter obtains digital input, provide numeral output and be made up of digital unit.In a kind of exemplary digital filtering application, the software of going up operation at digital signal processor (DSP) reads the input sample, carries out by the mathematical manipulation of the filter regulation that is designed and via digital to analog converter output result from analog to digital converter.Give regularly at indivedual filter parameters, the software defined desired signal that is used on DSP, realizing of filtering is handled equation and coefficient.
The FIR filter is to be used for digitally realizing the filter construction of required frequency response.Usually use consecutive delayer, multiplier and adder to realize that the FIR filter is to generate filter output.The value of the number of delayer and the used coefficient of multiplier depends on the Design of Filter corresponding with required frequency response.
The mixed signal treatment circuit uses pulse-width modulation (PWM) and many level PWMs signal.Become pwm signal to cause very little delay the real-time Simulation conversion of signals.Through allowing pwm signal to become a plurality of level rather than binary, might carry out addition and convergent-divergent to the delay version of pwm signal and pwm signal and do not lose any information.Use the delay version of pwm signal, to required transfer function configures FIR filter.
In certain embodiments, the FIR filter comprises the relative high bandwidth operational amplifier that serves as summer and integrator.The FIR filter also comprises the delay line with a plurality of delay line tap.Structure perhaps uses a plurality of transistors to come each unit delay of asynchronous structure delay line can to use two counters to come synchronously.At first use comparator the real-time Simulation conversion of signals to be become the PWM form with the triangular waveform maker.The wave frequency of triangular waveform is corresponding to the sampling rate in the comparable analog to digital converter.The pwm signal transmission is passed through tapped delay line to form one or more delay version of the pwm signal that needs in order to construct the FIR filter.Coefficient according to the FIR filter comes the delay version of convergent-divergent pwm signal and pwm signal, then pwm signal and delay version is sued for peace to form many level PWMs signal together.In order to remove the high fdrequency component of many level PWMs of gained signal, in based on the summer of high bandwidth operational amplifier, also comprise integrating function.Summation becomes the output analog signal with integrating circuit with many level PWMs conversion of signals.
Therefore the generation of pwm signal is almost instantaneous, in the time will import analog signal conversion and become pwm signal, introduces seldom delay (if delay is arranged).When many level PWMs conversion of signals is become the output analog signal, possibly introduce some delays, retardation depends on integration circuit time constant.
The mixed signal treatment circuit is with the duty ratio of pwm signal and amplitude is used for addition and convergent-divergent is realized to realize filter with the mixed signal circuit parts.Each pwm signal comprises the binary level information, and pwm signal is high or low, and wherein pwm signal is that high time quantum is a duty ratio during each cycle.All information in binary level PWM signal still exist when adding up to many level PWMs signal together.Many level PWMs of gained signal comprises duty cycle information and also comprises the amplitude information of representative input analog signal values.
In certain embodiments, use operational amplifier to realize summation and integrating function.When in noise removing is used, using, operational amplifier is following rp-op amp, and this amplifier generates the anti-phase analog signal based on the many level PWMs signal to the rp-op amp input.
Fig. 1 illustrates the simplified block diagram of the exemplary application of mixed signal treatment circuit in the noise removing head phone.Noise removing head phone 20 comprises microphone 22, mixed signal treatment circuit 24, audio tweeter 26, audio frequency apparatus input port 28, audio frequency processing circuit 30 and power supply 32.Microphone 22 reception environment noises and with ambient noise as the input analog signal send to mixed signal treatment circuit 24.Mixed signal treatment circuit 24 is handled the input analog signal to generate the anti-phase analog signal to audio tweeter 26 outputs.The anti-phase analog signal is configured to eliminate basically the input analog signal.Audio frequency apparatus input port 28 is configured to dock with the outer audio equipment that provides audio signal to be used for playback.At audio frequency apparatus input port 28 received audio signals and to audio frequency processing circuit 30 output audio signals, in this audio frequency processing circuit 30, handle and send audio signals and be used for playback to audio tweeter 26.Power supply 32 provides power to the parts of noise removing head phone 20.
Fig. 2 illustrates the sketch map according to the mixed signal treatment circuit of an embodiment.Analog signal is imported into first input of comparator 2.Triangular waveform maker 2 generates triangular waveform, and triangular waveform is imported into second input of comparator 2.Use triangular waveform to the input analog signal sampling, will import the pulse-width modulation territory that analog signal conversion becomes to be called pwm signal thus.Each cycle of pwm signal is corresponding to the cycle of modulated triangular wave shape.The triangular waveform cycle to the input analog signal sampling is called the sampling period during this time.The value of input analog signal in the sampling period is corresponding to the duty ratio of pwm signal.
Fig. 3 illustrates two sequential charts that postpone versions of the exemplary pwm signal exported on first three output line in Fig. 2 and this pwm signal.Show exemplary pwm signal at P1 to P5 on these five cycles, and cycle P1 is corresponding to the nearest time cycle.The pwm signal of on first output line, exporting is not postponed, and therefore in time corresponding among Fig. 2 from comparator 2 outputs and be input to the pwm signal of resistor R 1.The signal of on second output line, exporting corresponding among Fig. 2 from first delay line tap output and be input to first of resistor R 2 and postpone pwm signal.First postpones pwm signal is postponed one-period with respect to the pwm signal of on first output line, exporting.The signal of on the 3rd output line, exporting corresponding among Fig. 2 from second delay line tap output and be input to second of resistor R 3 and postpone pwm signal.Second postpones pwm signal is postponed one-period with respect to the first delay pwm signal of on second output line, exporting, and is postponed two cycles with respect to the pwm signal of on first output line, exporting.The signal of exporting on all the other output lines in Fig. 2 is postponed similarly.
The pwm signal that uses resistor network to come convergent-divergent on N output line, to export.In the exemplary configuration of Fig. 2, first output line is coupled to variable resistance R1, and second output line is coupled to variable resistance R2, and the 3rd output line is coupled to variable resistance R3, and the N+1 output line is coupled to variable resistance Rn+1.Though each of variable resistance R1 to Rn+1 is expressed as single resistor in Fig. 2, each that will understand variable resistance R1 to Rn+1 represented one or more resistor.Each output line is coupled to the resistor that is used for the amplitude convergent-divergent.
The mixed signal treatment circuit also comprises summation and integrating circuit.Each of variable resistance R1 to Rn+1 is coupled to this summation and integrating circuit.In the exemplary configuration shown in Fig. 2, summation comprises capacitor CI, resistor R I and operational amplifier 8 with integrating circuit.Variable resistance R1 to Rn+1 is coupled in first input of operational amplifier 8.Ground connection is coupled in second input of operational amplifier 8.The first input and output parallel coupled of capacitor CI and resistor R I and operational amplifier 8.Output resistor Rout is coupled to the output of operational amplifier 8.Operational amplifier 8 is output as analog output signal, and this signal is the output of mixed signal treatment circuit.
The zoom version of the zoom version of pwm signal and delay pwm signal is with generating many level PWMs signal, such as the signal of the many level PWMs among Fig. 5.Each cycle of many level PWMs signal is the summation of delay version of zoom version and pwm signal that is used for the correspondence sampling period of each pwm signal.For example, the cycle P1 of many level PWMs signal be to cycle P1 the pwm signal of the convergent-divergent on first output line, to cycle P1 at the delay pwm signal of the convergent-divergent on second output line, to the delay pwm signal of the convergent-divergent of cycle P1 on the 3rd output line be used for the summation of delay pwm signal of the convergent-divergent of each additional output line." height " of pwm signal and " low " value are expressed as respectively in Fig. 5 has value "+1 " and " 1 ".Many level PWMs signal is the summation of three convergent-divergent pwm signals on first output line, second output line and the 3rd output line, exporting.In a kind of exemplary application, according to the factor " 1 " convergent-divergent first pwm signal, according to the factor " 0.5 " convergent-divergent second pwm signal, and according to the factor " 0.25 " convergent-divergent the 3rd pwm signal.Three convergent-divergent pwm signals are sued for peace to form the many level PWMs signal shown in Fig. 5.
PWM tapped delay line, output line, resistor network and summation and integrating circuit form the FIR filter construction.The value of selecting each resistor is to be complementary with the required frequency response that is used for the FIR filter.The zoom factor of using to each output line is corresponding to one of coefficient in the FIR Design of Filter.Use variable resistance in design, to provide flexibility, realize the programmability of FIR filter thus to satisfy any value and phase place requirement.
In certain embodiments, operational amplifier comprises the summing circuit that is used for the pwm signal addition of each convergent-divergent of exporting from variable resistance R1 to Rn+1 is formed many level PWMs signal.Amplitude that in many level PWMs signal, comprises and duty cycle information are with generating from the analog signal of operational amplifier output.
Is linear operation with the PMW signal summation of convergent-divergent to form many level PWMs signal.In certain embodiments, summation is configured to low pass filter with integrating circuit.Owing to the linear operation that is summed in operational amplifier, so after summation, comprise low pass filter.Yet in alternative arrangements, low pass filter can be positioned before the summation.
In other embodiments, summing circuit is not to be included in the operational amplifier, is coupled between resistor network and the operational amplifier and replace.Fig. 4 illustrates the mixed signal treatment circuit of Fig. 2, and wherein summing circuit 10, summing circuit 12 and summing circuit 14 are coupled between resistor network and the operational amplifier.
In the exemplary application of mixed signal treatment circuit as a noise removing head phone part, the input analog signal is an ambient noise therein, and operational amplifier is a rp-op amp.Except many level PWMs conversion of signals is become the analog signal, rp-op amp many level PWMs signal that also reverses, thus make rp-op amp be output as the anti-phase analog signal of offsetting the input analog signal basically.Replace, can in the zoom factor that resistor network is used, comprise inverter functionality.
In Fig. 2, use variable resistance R1 to Rn+1 to realize the multiplication function of FIR filter.Generally speaking, can use and to realize multiplication function from the signal of comparator output or from the delay of signals version of one of delay line tap output with the conventional mlultiplying circuit of any kind of the signal multiplication of representing the corresponding filter factor that is used for convergent-divergent.
Use the FIR filter to realize above-mentioned mixed signal treatment circuit.Replace, can use infinite impulse response (IIR) filter to use similar principles.
Aspect specific embodiment, described the mixed signal treatment circuit, these embodiment incorporate details into so that understand the structure and the operating principle of mixed signal treatment circuit.Here be not in order to limit the scope of appended claims to quoting like this of specific embodiment and details thereof.Those skilled in the art are clear, can in the embodiment that selects for example, make revising and not breaking away from the spirit and the scope of mixed signal treatment circuit.
Claims (20)
1. signal processing circuit comprises:
A. change-over circuit is configured to receive input analog signal and the output pulse-width signal corresponding with said analog signal;
B. delay line is coupled to said change-over circuit to receive said pulse-width signal, and wherein said delay line comprises one or more delay line tap, and each delay line tap is configured to export the delay version of said pulse-width signal;
C. convergent-divergent circuit; Be coupled to said change-over circuit and said one or more delay line tap; Said one or more that wherein said convergent-divergent circuit is configured to said pulse-width signal of convergent-divergent and said pulse-width signal postpones each the delay version in the version, forms the pulse-width signal of a plurality of convergent-divergents thus; And
D. sue for peace and integrating circuit; Be coupled to said convergent-divergent circuit; Wherein said summation and integrating circuit are configured to receive the pulse-width signal of said a plurality of convergent-divergents; The pulse-width signal of said a plurality of convergent-divergents is summed to many level pulse width, and converts said many level pulse width to the output analog signal.
2. signal processing circuit according to claim 1; Wherein said change-over circuit comprises comparator and triangular waveform maker; Wherein said comparator is configured to said input analog signal and the triangular waveform that receives from said triangular waveform maker are compared, and exports said pulse-width signal in response to said comparison.
3. signal processing circuit according to claim 2; The cycle of wherein said pulse-width signal, the duty ratio in the concrete cycle of said pulse-width signal was corresponding to the amplitude of said input analog signal during the same period of said triangular waveform corresponding to the cycle of said triangular waveform.
4. signal processing circuit according to claim 3; Wherein postpone version and postponed the cycle of said pulse-width signal with respect to said pulse-width signal from first of the said pulse-width signal of first delay line tap output, and from each in succession each of said pulse-width signal of delay line tap output postpone the cycle that version is postponed said pulse-width signal in succession in succession.
5. signal processing circuit according to claim 1, wherein said convergent-divergent circuit comprises resistor network.
6. signal processing circuit according to claim 1, wherein said summation and integrating circuit comprise operational amplifier.
7. signal processing circuit according to claim 6, wherein said summation and integrating circuit comprise one or more summing circuit.
8. signal processing circuit according to claim 1, wherein said delay line, said convergent-divergent circuit and said summation and integrating circuit form finite impulse response filter.
9. signal processing circuit according to claim 8, wherein said finite impulse response filter is programmable.
10. signal processing circuit according to claim 1, wherein said signal processing circuit comprises the mixed signal treatment circuit.
11. signal processing circuit according to claim 10, wherein said mixed signal treatment circuit comprises many level pulse width treatment circuit.
12. a noise removing head phone comprises:
A. microphone is configured to testing environment noise and the generation input analog signal corresponding with said ambient noise;
B. signal processing circuit is coupled to said microphone, and wherein said signal processing circuit comprises:
I. change-over circuit is configured to receive said input analog signal and the output pulse-width signal corresponding with said analog signal;
Ii. delay line is coupled to said change-over circuit to receive said pulse-width signal, and wherein said delay line comprises one or more delay line tap, and each delay line tap is configured to export the delay version of said pulse-width signal;
Iii. convergent-divergent circuit; Be coupled to said change-over circuit and said one or more delay line tap; Said one or more that wherein said convergent-divergent circuit is configured to said pulse-width signal of convergent-divergent and said pulse-width signal postpones each the delay version in the version, forms the pulse-width signal of a plurality of convergent-divergents thus; And
Iv. sue for peace and integrating circuit; Be coupled to said convergent-divergent circuit; Wherein said summation and integrating circuit are configured to receive the pulse-width signal of said a plurality of convergent-divergents; The pulse-width signal of said a plurality of convergent-divergents is summed to many level pulse width, and converts said many level pulse width to the output analog signal, wherein said output analog signal is eliminated the part of said input analog signal basically; And
C. loud speaker is coupled to said signal processing circuit, and wherein said loud speaker is configured to generate audio frequency in response to said output analog signal.
13. a signal processing method comprises:
A. receive the input analog signal;
B. said analog signal conversion is become pulse-width signal;
C. generate one or more time delay version of said pulse-width signal;
D. said one or more of said pulse-width signal of convergent-divergent and said pulse-width signal postpones each the delay version in the version, forms the pulse-width signal of a plurality of convergent-divergents thus;
E. the pulse-width signal of said a plurality of convergent-divergents is sued for peace to form many level pulse width; And
F. convert said many level pulse width to the output analog signal.
14. method according to claim 13 wherein becomes said pulse-width signal to comprise said analog signal conversion said input analog signal and triangular waveform is compared, and generates said pulse-width signal in response to said comparison.
15. method according to claim 14; The cycle of wherein said pulse-width signal, the duty ratio in the concrete cycle of said pulse-width signal was corresponding to the amplitude of said input analog signal during the same period of said triangular waveform corresponding to the cycle of said triangular waveform.
16. method according to claim 15; First of wherein said pulse-width signal postpones version and is postponed the cycle of said pulse-width signal with respect to said pulse-width signal, and each of said pulse-width signal postpones the cycle that version is postponed said pulse-width signal in succession in succession.
17. method according to claim 13, wherein said convergent-divergent circuit comprises resistor network.
18. method according to claim 13, the said zoom factor that one or more postpones each the delay version in the version that wherein is applied to said pulse-width signal of convergent-divergent and said pulse-width signal is programmable.
19. method according to claim 13, wherein said signal processing comprise the mixed signal processing.
20. handling, method according to claim 19, wherein said mixed signal comprise many level pulse-width modulation processing.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US12/939,924 | 2010-11-04 | ||
| US12/939,924 US8217820B2 (en) | 2010-11-04 | 2010-11-04 | Using multi-level pulse width modulated signal for real time noise cancellation |
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| Publication Number | Publication Date |
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| CN102468831A true CN102468831A (en) | 2012-05-23 |
| CN102468831B CN102468831B (en) | 2016-03-30 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201110353599.3A Expired - Fee Related CN102468831B (en) | 2010-11-04 | 2011-11-03 | Many level pulse width are used for real-time noise to eliminate |
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| Country | Link |
|---|---|
| US (1) | US8217820B2 (en) |
| CN (1) | CN102468831B (en) |
| DE (1) | DE102011116217A1 (en) |
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| CN108700620A (en) * | 2015-10-14 | 2018-10-23 | 无线电力公司 | Phase in wireless energy transfer system and amplitude detection |
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| BRPI0822970B1 (en) * | 2008-07-30 | 2020-10-06 | Micro Motion, Inc | SIGNAL PROCESSOR, BUS CIRCUIT SYSTEM, AND METHOD FOR TRANSMITTING SIGNS FROM AN ANALOG SIGNAL GENERATOR TO AN ANALOG SIGNAL RECEIVER |
| DE102014116909B4 (en) * | 2014-11-19 | 2016-07-28 | Infineon Technologies Ag | A receiver, transmitter, method for retrieving an additional data value from a signal and method for transmitting a data value and an additional data value in a signal |
| DE102014116906B4 (en) * | 2014-11-19 | 2019-06-19 | Infineon Technologies Ag | A receiver, transmitter, method for determining a value encoded in a PWM signal and a method for transmitting a value encoded in a PWM signal |
| KR101647395B1 (en) | 2015-04-10 | 2016-08-10 | 서강대학교산학협력단 | Radiation apparatus and radiation detection signal processing method using bipolar time-over-threshold method |
| US10833666B1 (en) | 2019-09-17 | 2020-11-10 | Dialog Semiconductor (Uk) Limited | PWM controlled analog signal |
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| Publication number | Publication date |
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| DE102011116217A1 (en) | 2012-05-10 |
| US8217820B2 (en) | 2012-07-10 |
| CN102468831B (en) | 2016-03-30 |
| US20120114033A1 (en) | 2012-05-10 |
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